#!/usr/bin/env python3
# Copyright 2010-2025 Google LLC
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# [START program]
"""Simple Travelling Salesperson Problem (TSP) on a circuit board."""

# [START import]
import math
from ortools.constraint_solver import routing_enums_pb2
from ortools.constraint_solver import pywrapcp

# [END import]


# [START data_model]
def create_data_model():
    """Stores the data for the problem."""
    data = {}
    # Locations in block units
    data["locations"] = [
        # fmt: off
      (288, 149), (288, 129), (270, 133), (256, 141), (256, 157), (246, 157),
      (236, 169), (228, 169), (228, 161), (220, 169), (212, 169), (204, 169),
      (196, 169), (188, 169), (196, 161), (188, 145), (172, 145), (164, 145),
      (156, 145), (148, 145), (140, 145), (148, 169), (164, 169), (172, 169),
      (156, 169), (140, 169), (132, 169), (124, 169), (116, 161), (104, 153),
      (104, 161), (104, 169), (90, 165), (80, 157), (64, 157), (64, 165),
      (56, 169), (56, 161), (56, 153), (56, 145), (56, 137), (56, 129),
      (56, 121), (40, 121), (40, 129), (40, 137), (40, 145), (40, 153),
      (40, 161), (40, 169), (32, 169), (32, 161), (32, 153), (32, 145),
      (32, 137), (32, 129), (32, 121), (32, 113), (40, 113), (56, 113),
      (56, 105), (48, 99), (40, 99), (32, 97), (32, 89), (24, 89),
      (16, 97), (16, 109), (8, 109), (8, 97), (8, 89), (8, 81),
      (8, 73), (8, 65), (8, 57), (16, 57), (8, 49), (8, 41),
      (24, 45), (32, 41), (32, 49), (32, 57), (32, 65), (32, 73),
      (32, 81), (40, 83), (40, 73), (40, 63), (40, 51), (44, 43),
      (44, 35), (44, 27), (32, 25), (24, 25), (16, 25), (16, 17),
      (24, 17), (32, 17), (44, 11), (56, 9), (56, 17), (56, 25),
      (56, 33), (56, 41), (64, 41), (72, 41), (72, 49), (56, 49),
      (48, 51), (56, 57), (56, 65), (48, 63), (48, 73), (56, 73),
      (56, 81), (48, 83), (56, 89), (56, 97), (104, 97), (104, 105),
      (104, 113), (104, 121), (104, 129), (104, 137), (104, 145), (116, 145),
      (124, 145), (132, 145), (132, 137), (140, 137), (148, 137), (156, 137),
      (164, 137), (172, 125), (172, 117), (172, 109), (172, 101), (172, 93),
      (172, 85), (180, 85), (180, 77), (180, 69), (180, 61), (180, 53),
      (172, 53), (172, 61), (172, 69), (172, 77), (164, 81), (148, 85),
      (124, 85), (124, 93), (124, 109), (124, 125), (124, 117), (124, 101),
      (104, 89), (104, 81), (104, 73), (104, 65), (104, 49), (104, 41),
      (104, 33), (104, 25), (104, 17), (92, 9), (80, 9), (72, 9),
      (64, 21), (72, 25), (80, 25), (80, 25), (80, 41), (88, 49),
      (104, 57), (124, 69), (124, 77), (132, 81), (140, 65), (132, 61),
      (124, 61), (124, 53), (124, 45), (124, 37), (124, 29), (132, 21),
      (124, 21), (120, 9), (128, 9), (136, 9), (148, 9), (162, 9),
      (156, 25), (172, 21), (180, 21), (180, 29), (172, 29), (172, 37),
      (172, 45), (180, 45), (180, 37), (188, 41), (196, 49), (204, 57),
      (212, 65), (220, 73), (228, 69), (228, 77), (236, 77), (236, 69),
      (236, 61), (228, 61), (228, 53), (236, 53), (236, 45), (228, 45),
      (228, 37), (236, 37), (236, 29), (228, 29), (228, 21), (236, 21),
      (252, 21), (260, 29), (260, 37), (260, 45), (260, 53), (260, 61),
      (260, 69), (260, 77), (276, 77), (276, 69), (276, 61), (276, 53),
      (284, 53), (284, 61), (284, 69), (284, 77), (284, 85), (284, 93),
      (284, 101), (288, 109), (280, 109), (276, 101), (276, 93), (276, 85),
      (268, 97), (260, 109), (252, 101), (260, 93), (260, 85), (236, 85),
      (228, 85), (228, 93), (236, 93), (236, 101), (228, 101), (228, 109),
      (228, 117), (228, 125), (220, 125), (212, 117), (204, 109), (196, 101),
      (188, 93), (180, 93), (180, 101), (180, 109), (180, 117), (180, 125),
      (196, 145), (204, 145), (212, 145), (220, 145), (228, 145), (236, 145),
      (246, 141), (252, 125), (260, 129), (280, 133)
        # fmt: on
    ]
    data["num_vehicles"] = 1
    data["depot"] = 0
    return data
    # [END data_model]


# [START distance_callback]
def compute_euclidean_distance_matrix(locations):
    """Creates callback to return distance between points."""
    distances = {}
    for from_counter, from_node in enumerate(locations):
        distances[from_counter] = {}
        for to_counter, to_node in enumerate(locations):
            if from_counter == to_counter:
                distances[from_counter][to_counter] = 0
            else:
                # Euclidean distance
                distances[from_counter][to_counter] = int(
                    math.hypot((from_node[0] - to_node[0]), (from_node[1] - to_node[1]))
                )
    return distances
    # [END distance_callback]


# [START solution_printer]
def print_solution(manager, routing, solution):
    """Prints solution on console."""
    print(f"Objective: {solution.ObjectiveValue()}")
    index = routing.Start(0)
    plan_output = "Route:\n"
    route_distance = 0
    while not routing.IsEnd(index):
        plan_output += f" {manager.IndexToNode(index)} ->"
        previous_index = index
        index = solution.Value(routing.NextVar(index))
        route_distance += routing.GetArcCostForVehicle(previous_index, index, 0)
    plan_output += f" {manager.IndexToNode(index)}\n"
    print(plan_output)
    plan_output += f"Objective: {route_distance}m\n"
    # [END solution_printer]


def main():
    """Entry point of the program."""
    # Instantiate the data problem.
    # [START data]
    data = create_data_model()
    # [END data]

    # Create the routing index manager.
    # [START index_manager]
    manager = pywrapcp.RoutingIndexManager(
        len(data["locations"]), data["num_vehicles"], data["depot"]
    )
    # [END index_manager]

    # Create Routing Model.
    # [START routing_model]
    routing = pywrapcp.RoutingModel(manager)
    # [END routing_model]

    # [START transit_callback]
    distance_matrix = compute_euclidean_distance_matrix(data["locations"])

    def distance_callback(from_index, to_index):
        """Returns the distance between the two nodes."""
        # Convert from routing variable Index to distance matrix NodeIndex.
        from_node = manager.IndexToNode(from_index)
        to_node = manager.IndexToNode(to_index)
        return distance_matrix[from_node][to_node]

    transit_callback_index = routing.RegisterTransitCallback(distance_callback)
    # [END transit_callback]

    # Define cost of each arc.
    # [START arc_cost]
    routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)
    # [END arc_cost]

    # Setting first solution heuristic.
    # [START parameters]
    search_parameters = pywrapcp.DefaultRoutingSearchParameters()
    search_parameters.first_solution_strategy = (
        routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC
    )
    # [END parameters]

    # Solve the problem.
    # [START solve]
    solution = routing.SolveWithParameters(search_parameters)
    # [END solve]

    # Print solution on console.
    # [START print_solution]
    if solution:
        print_solution(manager, routing, solution)
    # [END print_solution]


if __name__ == "__main__":
    main()
# [END program]
